In his video message for the new year, the UN chief said climate change is not only a long-term problem but a clear and present danger, and "we cannot afford to be the generation that fiddled while the planet burned."
"But there is also hope," he said, adding that his New Year message is to the "greatest source of that hope, the world's young people."
Paying tribute to the power of youth around the planet, Guterres said that from climate action to gender equality to social justice and human rights, young generation is on the frontlines and in the headlines.
Noting that young people are "rightly demanding a role in shaping the future," the secretary-general added that "the United Nations stands with you - and belongs to you."
He also said the world needs young people to keep speaking out and keeping up the pressure, in a year in which the UN marks its 75th anniversary of founding.